Innovations in electronics and technology have made it possible to incorporate a variety of advanced features on automotive vehicles. Various sensing technologies have been developed for detecting objects or monitoring the surroundings in a vicinity or pathway of a vehicle. Such systems are useful for parking assist, lane departure detection and cruise control adjustment features, for example.
More recently, automated vehicle features have become possible to allow for autonomous or semi-autonomous vehicle control. Sensors for such systems may incorporate LIDAR (light detection and ranging) or radar for detecting an object or another vehicle in the pathway of or otherwise near the vehicle. Depending on the approach speed, the cruise control setting may be automatically adjusted to reduce the speed of the vehicle based on detecting another vehicle in the pathway of the vehicle, for example.
One aspect of such sensing technologies includes determining an angle associated with the detection for properly identifying the position of an object external to the vehicle. With known RADAR systems, angle resolution depends on the spacing between the detector elements and the overall antenna or receiver aperture. Automotive sensing devices typically have a small number of transmit and receive channels. These considerations have made the placement of RADAR or LIDAR detector elements critical to achieve a desired level of performance.
There are challenges associated with designing and utilizing such devices on automotive vehicles. While a larger aperture size can yield better angular discrimination, it does not come without a cost. Increasing the aperture size tends to introduce grating lobes in the spectrum especially when the array spacing is greater than one-half a wavelength as demonstrated by the Nyqist-Shannon sampling theorem. Typical radar detector design includes placing the detector elements in an array with a one-half wavelength spacing between them to avoid grating lobes.
Those skilled in the art are striving to improve various aspects of detectors useful on vehicles.